Pneumatic pressure operated device



March 14, 1950 I H. J. SADLER ET AL PNEUMATIC PRESSURE-OPERATED. DEVICE2 Sheets-Sheet 1 Filed April 3, 1948 March 14, 1950 H. J. SADLER ET AL2,500,383

PNEUMATIC PRESSURE-OPERATED DEVICE Filed April 5, 1948 r 2 Sheets-Sheet2 Patented Mar. 14, 1959 PNEUMATIC PRESSURE OPERATED DEVICE Harry J.Sadler and ErnestE. Cook, Minneapolis,

Minn; said Geek assignor to said Sadler Application April 3, 1948,Serial-No. 18,754

11 Claims.

under pressure from one thereof to the other thereof.

Still more specifically; an important object of our invention is theprovision of a novel chuck or collet closer utilizing our novel valvemechanism and apparatus for. transfer of fluid under pressure from astationary to a relatively movable part thereof, whereby to contract andrelease said collet.

A still further object of our invention is the provision of a device ofthe class above-described which includes relatively few movable parts,which is extremely durable in construction, which is inexpensive tomanufacture, and which is efficient and trouble-free in operation.

The above and still further objects-of our invention will becomeapparent from the following detailed specification, appended claims, andattached drawings;

Referring to the drawings, wherein like characters indicate likepartsthroughout the several views:

Fig". l is a view in front elevation of a collet chuck built inaccordance with our invention and mounted upon a; conventional lathe,some parts being broken away andsome. parts shown in section;

Fig. 2 is a view, partly in horizontal section and partly in diagram,taken substantially on the line 2-2. of Fig. 1. and turned. 90 withrespect thereto;

Fig. 3 is afragmentary-cross section, taken on the line 3-45: of Fig.2,.v with some parts being broken away;

Fig. 4 is axfragmentary cross section, taken substantially on the linei-d of Fig. 2;

Fig; 5 is a; fragmentary detail in section, taken onthe line 55 of Fig.2;

Fig. 6 is a transverse section, taken on the line 55 of Fig. 2; and

Fig, 7 is an enlarged fragmentary sectional detail, taken on the; line'!T-of Fig. 3.

Referring; with; greater particularly to the drawings, the numeral!indicates, in its entirety,

aheador. casinglhaving acup-shaped front wall Zandarelatively, flat rearwall 3 connected to the outer peripheral edge of said; front wall 2 bymeans ofmachinescrews or the like l. The elements Zanddare preferablymade from lightweight; material such as aluminum, in order to reduce theweight of. the entire device. The rear wall}: is-lp-referably castaround and secured fast on an. annular, bushing; 5, preferably made fromsteel or other material of considerably greater hardness thanthe Wa1l3-The bushing 52.15. internally: threaded to enga e the threaded end E5.of; a hollow rotary; spindle l which may berotatively carried bythe headof a conventional, lathe,,, screw, machine, or the like, not shown.- Aspacer 8;,and a collar llperform no particular function with; regard tothe instant invention, being merely parts, of conventional lathestructure.

Elements; l, 2', and 5; cooperate to produce a circular cavity;v la intowhich axially projects an annular, bearing boss portion l l of thebushing.;5.- Theinner peripheral wall section of the front; wall 2isprovided with a, sleeve l2 which may be made of suitablebearingmaterial. An annular pistonl3 is axially slidably mounted in the, cavityill; with the inner periphery thereof snugly encompassing. the bearingboss H and the outer periphery thereof slidably engaging the: sleeve l2,Annular seals i l and i5 prevent leakageof, fluid under pressure betweenthe piston l3 and the'bearing block H and sleeve l2 respectively. Thepiston l3, a portion of the sleeve l2, the rear wall 3, and bearing bossM define a. pressure chamber It, the piston it being inthe nature of amovable wall thereof. The piston is is yield-ingly biased in onedirection (toward a pressure chamber-contracting position) by means ofaplurality of circumferentially-spaced coil compression-springs l'lseated in alignedpockets l8 and 29 in the front wall I and piston l3respectively. An annular seal 26 is interposed in the connection betweenthe peripheral portion. of the front wall Zand the rear wall 3topre-vent leakage of fluid from the chamber; l6 therethrough The pistonI3 is provided with an axially forwardly-projecting annular flange 21!,which is internally-threaded to; receive an externallythreaded collarwhich is provided with a plurality of: circumferentially spac edinwardly opening cup-shaped pockets-23 which snugly receive theballelike radially outer'ends 2,. l'of radially-projectinglever'armslfi. The lever arms 25 are disposed withinradialchannels 26.in an annular ring 21, which is internally-threaded to receive thethreaded end 28 of a collet 29, having a plurality of jaws 38 formed byslotting the collet 29 axially, as indicated at 3i, in the conventionalmanner. The collet 29 is provided with a tapered peripheral outer face32 which is adapted to be engaged by a corresponding tapered portion 33of an annular contraction ring 34 axially slidable on the outerperipheral surface of the collet '29 and in an opening or bore 35.Forward movement of the contraction ring 34 is lifted by engagement of acircumferential flange 36 with a shoulder in the front Wall 2 formed bya counterbore therein.

The bottoms of the channels adjacent the outer ends in the annular ring2'! are each provided with a projecting fulcrum-forming edge or shoulder3'7 which is adapted to engage the intermediate portion of itsrespective lever arm 25. As shown in Fig. 2, the radially inner ends ofthe lever arms 25 abut the inner end of the contraction ring 35.Centering of the collet 29 with respect to the piston i3 is insured bythe seating of an annular flange 38 On the ring 2? within an annulargroove 39 in the piston 13.

From the above, it should be obvious that movement of the piston 13,against the bias of the springs I'i, axially in the direction of thecollet 29, or from the left to the right with respect to Fig. 2, removesthe axial thrust imparted by the radially inner ends of lever arms 25upon the contraction ring 34. Removal of axial pressure against thecontraction ring 34 allows the same to slide axially from the right tothe left with respect to Fig. 2, thereby releasing the grip of theseveral jaws 36 upon the stock or workpiece contained therein but notshown. Movement of the piston 13 in a direction from the right to theleft with respect to Fig. 2 under bias of the springs ll, on the otherhand, causes the radial lever arms 25 to engage the edges or shoulders3'], whereby to produce an axial thrust of the inner ends of the arms 25against the contraction ring 34 in a direction to contract the jaws ofthe collet 29.

The collet 29 is provided with a plurality,.as shown four, ofcircumferentially-spaced keyways El], and which are adapted to slidablyseat the inner ends of diametrically-opposed pins ll. The pins M areprovided with head portions 42 which are slidable in radial bores 43 inthe central portion of the front wall 2. The pins 4! extend radiallythrough diametrically-opposed radial passages M in the contraction ring34 and are biased in a radially outward direction by means of coilcompression springs 45 (see particularly Fig. 6). It will be seenparticularly by reference to Fig. 2, that the bores 13 are locatedoutwardly of the main body portion of the front wall 2 in an axiallyprojecting hub portion 2' thereof. A ring or collar 4-5 encompasses andis rotatably slidable on the outer periphery of the hub 2 and isprovided with a pair of diametrically-opposed recesses 4'! that areadapted to receive, under rotary movements of the collar to, the heads42 of the pins M. The pins 4| are of such a length, that when the heads32 thereof are contained within the recesses l! the inner ends 4| arespring pressed radially outwardly of the keyways ill so that the collet29 may be rotated with respect to the annular ring 21. Rotation of thecollet 29 with respect to the ring 2'! due to the threaded engagementtherein provides axial adjustment of the collet 29 with respect to thecontraction ring 34. When the proper adjustment has been obto close theinlet port 6!.

tained, the ring 46 is rotated to a point where the recesses 47 arecircumferentially opposite from the heads 12 so that the pins ii aremoved into opposed keyways it. The recesses 41 are so shaped thatrotation of the ring 46 moves the heads 42 therefrom with a cammingaction against bias of the springs 45. Accidental rotation of the ring36 with respect to the hub 2' is prevented by a pair ofdiametrically-opposed spring pressed bore elements 38 adapted to engagecircumferentially-spaced detents 19. The ring 4%; at one and engages theouter surface of the wall 2 and is limited in axial movements outwardlyof the wall 2 by means of an annular plate 58 which is secured to theouter end of the hub 2' by means of machine screws or the like 5| (seeparticularly Figs. 1 and 2). The internal and external diameters of theplate 56 are such that the plate so does not interfere with freerotating movements of the ring 36 nor free axial movements of thecontraction ring 34.

The rear wall 3 is formed to provide an annular inlet passage 52 whichcommunicates with the pressure chamber 13 through a pair ofdiametrically-opposed disc-like check valves 53. The check valves arecontained in recesses 54 in the rear wall 3 and are secured by screws orthe like 55, whereby to be seated over valve openings 52' communicatingwith the passage 52 and the pressure chamber :5. The rear wall 3 ischanneled adjacent the inlet passage 52 to receive an annular checkvalve 56 which is held in place by means of a clamping ring 51 which isrigidly secured to the wall 3 by means of a plurality of screws 58. Asshown in Fig. 2, the rear wall 3 is provided with a radially inwardlyprojecting flange 55 which is bevelled at its inner edge and cooperateswith a bevelled outer edge 6B of the ring 5'. to form an inlet port 61.The annular check valve 55 may be made from any resilient flexiblematerial, but preferably, and as shown, is made from soft rubber or thelike and is normally seated against the axially inner ends of the flange59 and clamping ring 57 whereby The annular passage 52 communicates withatmosphere exterior of the head i through a restricted bleeder orifice52 and an internal passageway 63.

Air is exhausted from the pressure chamber l5 through a passage 64leading therefrom into an exhaust valve chamber 65, and from thencethrough a passage 58 into a cavity I ll. From thence, the exhaust airfrom the pressure chamher it is dissipated outwardly from the cavity lothrough the slots 3| in the collet 29. An exhaust valve 61 is providedat one end with a head 68 that is preferably rectangular in crosssection and which is cone-shaped at its extreme outer end. Thecircumferentially-spaced outer end is covered with a sealing cap 69which, under axial movements of the valve 6i, is adapted to seal off oneend of the passage 66. The valve 6'! is proided with an axiallyextending reduced shank 1B which terminates at its rear end in acircumferential flange H which is preferably made of relatively softflexible material such as rubber or the like and which is held againstaxial movement adjacent its peripheral portion by engagement at one sidethereof with an annular shoulder l2 formed in the peripheral portion ofthe wall 2. The flange H is held against axial movement in the oppositedirection by means of an annular stop collar 13 which abuts the outerperipheral portion of the rear wall 3. It will be seen, particularly byreference to Figs. 2 and 7, that the atom-see passageway-63communicateswiththe-end of the chamber 65 opposite the exhaustpassagefit, but is sealed again st communication with the exhaustpassages ti and 66 by the resilient flange H. The flange H, due to itsresilient nature, permits axial movement of the valve 6'3 within thechamber 55 for a purpose which willhereinafter become apparent.

Fluid medium underl'elatively high pressure, preferably air, is appliedto the annular port 6! and against the check valve 56 in a highlyconcentrated jet by means of a nozzle i l which is adapted to be locatedin the path or" travel of the annular port A hose coupling 75 hasscrewthreaded engagement with the nozzle l l andas shown in Figs. 1 and2 is clamped in a split block 76 by means of a nut-equipped boltl'lwhich also secures the block it to a bracket it. The bracket '18 maybe fastened to the machine tool in any number of ways, but as shown inFig. 1 rests upon a lathe bed is and is firmly held thereon by means ofa clamp Bil and a clamping screw 8i. As shown diagrammatically in Fig.2, air is supplied to the coupling 55 and nozzle i l from a pressuretank 82 and a pump or the like 83 through conduit means 84. A valve 85is interposed in the conduit 84 between the tank 82 and the coupling l5,and may be either automatically or manually controlled.

As above pointed out, the check valve 56 normally closes the annularport 6!, but due to its flexible and resilient nature is adapted tobecome unseated and to open the port 6: to communication with theannular passage 52 at localized areas of an extent very slightly largerthan the cross sectional area of the jet of fluid projected thereagainst(see particularly Fig. 5). Air admitt-ed to the annular passage 52passes through the openings 52', unseating. the check valves 53, andinto the annular pressure chamber E6. Simultaneously, the air underpressure in the passage passes through the passageway t3 and exertspressure against the flange 7 i, whereby to move the valve ii to closeexhaust passage 66. size of the bleeder orifice 52 is such that airescapes therethrough at a much slower rate than it is being projectedinto the annular passage 52 by means of the nozzle E i, so that pressureis built up within the pressure chamber 55 at a I the annular piston I3in a direction from the it to the ri ht with respect to Fig. 2. Asherenbeiore described, such movement of the piston .eases pressure ofthe radial lever arms 'ainst the contraction ring 34 and subsequent'-'=ease of gripping pressure of the ccllet 29 ainst a workpiece heldtherein. Cutting off of he fluid pressure supplied to the nozzle Hi,which may be caused by manipulation of the valve 85, allows the annularcheck valve 56 to seat against the flange 59 and seal the port 6! overits entire circumferential area. This rescaling is enhanced by therelatively high fluid pressure within the passage 52. With the cuttingoff of the fluid supply from the nozzle it, however, the fluid or aircontinues to bleed from the orificeiiz and a differential in pressure isformed between the passage 5'2 and the pressure chamber it. It will benoted that fluid pressure in the pressure chamher it and in the valvechamber 55 is equal due to the connection therebetween of the exhaustpassage The consequent diiierential in pressure in the valve chamber 65and the annular passage 52 causesthe valve 5? to move from the right tothe left with respect to Figs. 2 and 7,

.te suiiicient to cause relatively rapid movement thereby disengagingthe sealing cap 69 from the passage 56 and allowing rapid exhaust orfluid from the pressure chamber 18. It will be remembered that thepiston i3 is under yielding bias of the several springs H to move'in adirection to exhaust fluid fromthepressure chamber it" or from the rightto the left with respect to Fig. 2, and-movement in this directioncauses the lever arms 25 to move the contraction ring Ed in a directionto close the jaws til of the collet 29.

In operation, it may be assumed that the fluid supply is cut off fromthe nozzle it and that spindle l and headl are under rotation atoperating speed. With the pressure supply cut off, the springs ll havemoved the piston is and means carried thereby to close the collet 29over the workpiece. Opening of the valve allows fluid under pressure topass through the nozzle it in a concentrated highly localized jetwhichimpinges against the annular check valve 55 through the annular port ti,causing the valve 56 to become unseated only atthe point of impact Ofthe jet thereagainst. It will be appreciated that this point of'impacttravels rapidly about the entire periphery of the valve 58 due to itsrotation relative to the nozzle i i. In other words, the outerperipheral edge of the valve 58 assumes the position of a ripple or wave(see particularly Fig. 5), which ripple travels continuously about theperiphery thereof under rotation of the head as long as the jet of thefluid is applied thereto. Normal seating of the valve 56 against theflange 59in addition topressure of the fluid built up within the passage52 insures the sealing of the annular port 65 at all points about theperiphery thereof other than that at which the jet occurs, thus insuringagainst any leakage of iluid out-, wardly through the port 5!. Whensufficient pressure has been built up withinthe pressure chamber It, themovable wall element or piston 83 moves in a direction to release thecollet 29 from the action of the contraction ring 3t. At this point, theworkpiece may be removed and another inserted or material fed axiallythrough the spindle l and collet it for machining thereof. As soon asthe material has been properly fed through the collet 29, the valve 85may be closed, thereby shutting off fluid supply to the nozzle. Bleedingof fluid through the orifice 52 to atmosphere rapidly causes adifferential in pressure therefrom between the annular passage 52 andthe pressure chamber it. As hereinbeore described, this differential inpressure allows the exhaust valve to open the passage 56, whereby toallow rapid escape'of the air or fluid from the pressure chamber it toatmosphere through the cavity ill under bias of the springs it upon thepiston or movable wall element It. Of course, movement of the piston i3caused by the springs I? again causes the contraction ring 3 3 to closethe collet ZQ'upon the workpiece.

Our improved device has been thoroughly tested and found to be extremelyeilicient and rapid in its operation. In fact, it has been found thatour device may be operated entirely automatically by the use of anautomatic valve in connection with an automatic screw machine withentirely satisfactory results.

Although the foregoing description is necessarily of detailed character,in order that the invention may be completely set forth, it is to beunder-stood that the specific terminology is not intended to berestrictive or confining, and that various rearrangementsof-parts andmodifica..-. tions of detail may be-resorted to without departing fromthe scope or spirit of the invention as herein claimed.

We claim:

1. In a fluid pressure-operated device, a rotary head structure defininga pressure chamber and a port through a wall thereof connecting saidpressure chamber to atmosphere, an inwardlyopening check valve closingsaid port, and a nonrotary nozzle for directing a highly concentratedjet of fluid under pressure toward said head and the path of rotarytravel of the check valveequipped port.

2. In a fluid pressure-operated device, a rotary head structureincorporating means for mounting on a rotary shaft, said head structuredefining a pressure chamber and a port through a wall thereof connectingthe pressure chamber to atmosphere, an inwardly-opening check valveclosing said port and having a surface exposed to atmosphere throughsaid port, and a nonrotary nozzle adapted for connection to a source offluid under pressure and incorporating mounting means adapting it to bepositioned to direct a highly concentrated jet of fluid toward the headand the path of travel of the check valveequipped port, said check valveopening under the impact of the jet when the pressure of the jet againstthe outer surface of the check valve exceeds the pressure against theinner surface thereof.

3. In a fluid-operated device, a head structure, said head structuredefining a pressure chamber and an elongated port through a wall thereofconnecting said valve chamber to atmosphere, an inwardly-opening checkvalve closing said port and having a surface exposed to atmospherethrough said port, a nozzle adapted for connection to a source of fluidunder pressure and incorporating mounting means adapting it to bepositioned to direct a concentrated jet of fluid toward said head andcheck valve-equipped port, said head and said nozzle being mounted forrelative movements one with respect to the other, said check valveclosing said port at all points where internal pressure exceedsatmospheric pressure and having sufficient resilience to permitunseating at localized areas of much less extent than the length of thevalve port, Whereby upon relative movement of said head with respect tosaid nozzle said valve will be opened only at the constantly changinglocalized area adjacent said nozzle by the concentrated fluid jetdirected by said nozzle against said valve.

4. In a fluid pressure-operated device, a rotary head structureincorporating means for mounting on a rotary shaft, said head structuredefining a pressure chamber and an elongated arcuate port through a wallthereof connecting said chamber to atmosphere, an inwardly-opening checkvalve closing said port and having a surface exposed to atmospherethrough said port, and a non-rotary nozzle adapted for connection to asource of fluid under pressure and incorporating mounting means adaptingit to be positioned to direct a concentrated jet of fluid to ward thehead and the path of travel of the check valve equipped port, said checkvalve closing said port at all points where internal pressure exceedsatmospheric pressure and having suflicient resilience to permitunseating at localized areas of much less circumferential extent thanthe circumferential length of the valve port, whereby upon rotation ofsaid head said valve will be opened only at the constantly changinglocalized area adjacent said nozzle by th concentrated fluid jetdirected by said nozzle against said valve.

5. The structure defined in claim 4 in which said port and said valveare annular in shape and are concentric to the axis of rotation of saidhead.

6. In a fluid pressure-operated device, a rotary head structureincorporating means for mounting on a rotary shaft, said head structuredefining a pressure chamber, an annular port in one wall thereof openingto atmosphere, and an inlet passage connecting said port to saidpressure chamber, flexible inwardly-opening annular check valve normallyclosing said port and having a surface exposed to atmosphere throughsaid port, a non-rotary nozzle adapted for connection to a source offluid under pressure and incorporating mounting means adapting it to bepositioned to direct a highly concentrated jet of fluid toward the headand the exposed surface of the check valve upon rotation of said head,said check valve closing the port at all points where internal pressureexceeds atmospheric pressure and having sumcient resilience to permitunseating at localized areas, whereby upon rotation of said head saidvalve will be opened only at the constantly changing localized areaadjacent said nozzle by the concentrated fluid jet directed by saidnozzle against said valve, a check valve in the passage between saidfirst-mentioned check valve and said pressure chamber permitting passageof fluid only from said passage to said chamber, means for creating adifferential in fluid pressure between said pressure chamber and saidinlet passage, and an exhaust valve for said pressure chamber responsiveto differential in fluid pressure between the pressure chamber and saidpassage.

7. In a fluid pressure-operated device, a rotary head structureincorporating means for mounting on a rotary shaft, said head structuredefining a pressure chamber, an annular port in one Wall thereof openingto atmosphere, and an inlet passage connecting said port to saidpressure chamber, a flexible inwardly-opening annular check valvenormally closing said port and having a surfac exposed to atmospherethrough said port, a non-rotary nozzle adapted for connection to asource of fluid under pressure and incorporating mounting means adaptingit to be positioned to direct a highly concentrated jet of fluid towardthe head and the exposed surface of the check valve upon rotation ofsaid head, said check valve closing the port at all points whereinternal pressure exceeds atmospheric pressure and having sufficientresilience to permit unseating at localized areas, whereby upon rotationof said head said valve will be opened only at the constantly changinglocalized area adjacent said nozzle by the concentrated fluid jetdirected by said nozzle against said valve, a check valve in the passagebetween said firstmentioned check valve and said pressure chamberpermitting passage of fluid only from said passage to said chamber,means for creating a differential in fluid pressure between saidpressure chamber and said inlet passage, said means including a bleederorifice connecting said inlet passage to atmosphere, said head having anexhaust passage connecting said pressure chamber with atmosphere, and anexhaust valve in said exhaust passage responsive to diiferential influid pressure between said pressure chamber and said inlet passage toexhaust fluid from said pressure 76 chamber when the pressure in saidinlet passage is less than the pressure within said pressure chamber.

8. In a device of the class described, a collet and a collet closer,said collet closer comprising a rotary head structure incorporatingmeans for mountin on a rotary shaft, said head structure defining apressure chamber and a port through a Wall thereof connecting thepressure chamber to atmosphere, an inwardly-opening check valve closingsaid port and having a surface exposed to atmosphere through said port,a non-rotary nozzle adapted for connection to a source of fluid underpressure and incorporating mounting means adapting it to be positionedto direct a highly concentrated jet of fluid against the exposed surfaceof said valve upon rotation of the head, said check valve opening underthe impact of the jet when the pressure of the jet against the outersurface of the check valve exceeds the pressure against the innersurface thereof, one of the walls of said pressure chamber being movablewith respect to the others thereof, a contraction ring mountedconcentrically on said collet for axial sliding movements and adapted tocontract and release the jaws thereof under said sliding movements, andmeans operatively connecting the movable wall of said pressure chamberwith said contraction ring.

9. In a device of the class described, a collet having a taperedperipheral outer face, and closer mechanism for said collet, said closermechanism comprising a head structure incorporating means for mountingon a rotary shaft, said head structure defining a pressure chamber, anannular port in one. wall thereof opening to atmosphere, and a passageconnecting said port to said pressure chamber, a flexibleinwardly-opening annular check valve normally closing said port andhaving a surface exposed to atmosphere through said port, a non-rotarynozzle adapted for connection to a source of fluid under pressure andincorporating mounting means adapting it to be positioned to direct ahighly concentrated jet of fluid toward the head and the exposed surfaceof the check valve, said check valve closing the port at all pointswhere internal pressure exceeds atmospheric pressure and havingsufficient resilience to permit unseating at localized areas,

whereby upon rotation of said head said valve will be opened only at theconstantly changing localized area adjacent said nozzle by theconcentrated fluid jet directed by said nozzle against said valve, oneof the walls of said pressure chamber being movable with respect to theothers thereof, a contraction ring axially slidably mounted on saidcollet and having a tapered portion engageable with the taperedperipheral outer surface of said collet, whereby to contract the jaws ofsaid collet and release the same upon axial movements of saidcontraction ring with respect to said collet, and means operativelyconnecting said contraction ring with the movable wall of said pressurechamber.

10. The structure defined in claim 9 in which said head is provided withan exhaust passage connecting said pressure chamber with atmosphere anda restricted bleeder orifice connecting said inlet passage withatmosphere, and in further combination with an exhaust valve in saidexhaust passage responsive to differential in fluid pressure between thepressure chamber and said inlet passage.

11. In a fluid pressure-operated device, a rotary head structureincorporating means for mounting on a rotary shaft, said head structuredefining a pressure chamber and an elongated arcuate port through a wallthereof connecting the pressure chamber to atmosphere, aninwardly-opening check valve closing said port and having a surfaceexposed to atmosphere through said port, a non-rotary nozzle adapted forconnection to a source of fluid under pressure and incorporatingmounting means adapting it to be positioned to direct a highlyconcentrated jet of fiuid toward the head and the exposed surface ofsaid valve, said check valve opening under the impact of the jet whenthe pressure of the jet against the outer surface thereof exceeds thepressure against the inner surface thereof, one of the walls of saidpressure chamber being movable with respect to the others thereof, meansbiasing said movable wall in one direction, and means for controllingthe flow of fluid through said nozzle and said valve, whereby to movesaid movable wall against the bias applied thereto, said port and valvebeing angular in shape and concentric with the axis of rotation of saidhead.

HARRY J. SADLER. ERNEST E. COOK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,291,147 Carlsen July 28, 19422,383,094 Walder Aug. 21, 1945 2,392,999 Redmer Jan. 15, 1946 2,393,458Cook Jan. 22, 1946 2,454,593 Chalicarne Nov. 23, 1948

